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[Qemu-devel] [PULL 2/2] tcg/i386: Always use TZCNT when available
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PULL 2/2] tcg/i386: Always use TZCNT when available |
Date: |
Tue, 17 Jan 2017 15:03:32 -0800 |
I think this is cleaner than sometimes using BSF.
Signed-off-by: Richard Henderson <address@hidden>
---
tcg/i386/tcg-target.inc.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/tcg/i386/tcg-target.inc.c b/tcg/i386/tcg-target.inc.c
index 6489b73..5918008 100644
--- a/tcg/i386/tcg-target.inc.c
+++ b/tcg/i386/tcg-target.inc.c
@@ -1143,10 +1143,14 @@ static void tcg_out_movcond64(TCGContext *s, TCGCond
cond, TCGReg dest,
static void tcg_out_ctz(TCGContext *s, int rexw, TCGReg dest, TCGReg arg1,
TCGArg arg2, bool const_a2)
{
- if (const_a2) {
- tcg_debug_assert(have_bmi1);
- tcg_debug_assert(arg2 == (rexw ? 64 : 32));
+ if (have_bmi1) {
tcg_out_modrm(s, OPC_TZCNT + rexw, dest, arg1);
+ if (const_a2) {
+ tcg_debug_assert(arg2 == (rexw ? 64 : 32));
+ } else {
+ tcg_debug_assert(dest != arg2);
+ tcg_out_cmov(s, TCG_COND_LTU, rexw, dest, arg2);
+ }
} else {
tcg_debug_assert(dest != arg2);
tcg_out_modrm(s, OPC_BSF + rexw, dest, arg1);
--
2.9.3